1. Field of the Invention
The invention relates to the transference of data between two systems independent of the form in which the data is kept on the respective systems, and in particular to providing an efficient means of communicating data between systems and devices.
2. Description of the Related Art
The growth of computing-related devices has not been limited to personal computers or workstations. The number of personal computing devices has grown substantially in both type and format. Small, hand-held computers carry a multitude of contact, personal, document, and other information and are sophisticated enough to allow a user to fax, send e-mails, and communicate in other ways wirelessly. Even advanced cellular phones carry enough memory and processing power to store contact information, surf the web, and provide text messaging. Along with the growth in the sophistication of these devices, the need to transfer information between them has grown significantly as well.
With a multitude of different device types on the market, keeping information between the different devices synchronized has become increasingly problematic. For example, if an individual keeps a calendar of information on a personal computer in his or her office using a particular personal information manager application, the individual would generally like to have the same information available in a cellular phone, hand-held organizer, and perhaps a home personal computer. The individual may additionally have a notebook computer which requires synchronizing file data such as presentations or working documents between the notebook and the office computer.
Until now, synchronization between both documents and personal information managers has occurred through direct connection between the devices, and generally directly between applications such as a personal information manager in one device and a personal information manager in another device or using an intermediary sync-mapping program.
One example of this is the prevalent use of the 3Com Palm® OS-based organizer, such as the 3Com Palm® series of computing devices, which uses its own calendaring system, yet lets users synchronize the data therein with a variety of different personal information manager software packages, such as Symantec's ACT!™, Microsoft's Outlook®, and other systems. In this example, an intermediary synchronization program such as Puma Technology, Inc.'s Intellisync® is required. Intellisync® is an application program which runs on both the hand-held device and the computer which stores the information data and maps data systems between non-uniform data records.
In other cases, direct transfer between applications such as transfer between Microsoft's Outlook® computer-based client and Microsoft's Windows CE “Pocket Outlook” application, is possible. Nevertheless, in both cases, synchronization occurs through direct connection between a personal computer and the personal computing device. While this connection is generally via a cable directly connecting, for example, a Palm® device in a cradle to the personal computer, the connection may be wireless as well.
One component of these synchronization systems is that the synchronization process must be able to delineate between when changes are made to specific databases and must make a decision about whether to replace the changed field. Normally, this is measured by a change in one database, and no-change in a second database. In some cases, both databases will have changed between syncs. In this case, the sync operation must determine which of the two changes, which has been made is to “win” and replace the other during the sync. Generally, this determinant of whether a conflict exists allows some means for letting the user resolve the conflict.
In a technical sense, synchronization in this manner is generally accomplished by the copying of full records between systems. At some level, a ell, user is generally required to map data fields from one application to another and specify which data fields are assigned to which corresponding field in a different device. Less mapping is required where developers more robustly support various platforms of applications.
In many instances, the data to be synchronized is generally in the form of text data such as records of addresses, contact information, calendar information, notes and other types of contact information. In certain instances, data to be synchronized will be binary format of executable files or word processor-specific documents. In many cases where document synchronization is required, the synchronization routine simply determines whether or not the documents in question have changed, and uses a time-based representation to determine which of the two files is newer, and replaces the older file with the newer file to achieve synchronization, as long as the older of the two files was in fact not changed. This is the model used in the familiar “Briefcase” function in Microsoft Windows-based systems. If both files have changed, then the synchronization routine presents the option of conflict resolution to the user.
Generally, such synchronization schemes are relatively inefficient since they require full bandwidth of the document or binary file to be transferred via the synchronization link. In addition, a change log is typically generated with each synchronization operation to record the changes in any given data record. In a situation where a large number of change logs have been generated (and stored in a server's memory), the sequence of downloading and applying each change log often results in the unnecessary download of data. A separate transaction is required for each occurrence of an item record in the change log sequence and it is possible for the same field in a record to be updated many times during a single synchronization operation.
Accordingly, there is a need for a change log aggregation and optimization mechanism that will more efficiently utilize memory storage space and speed up the synchronization process.